Barnsley set up a Carabao Cup third-round tie at Chelsea with a convincing win at Championship rivals Middlesbrough.
The visitors took the lead through Patrick Schmidt before Jordan Williams kept his composure to make it 2-0 before half-time.
Marcus Tavernier forced a save from Tykes goalkeeper Brad Collins after the break.
Despite late pressure that was as good as it got for Boro.
Both teams went into the game after 1-0 defeats in the weekend's opening league games of the season.
Boro started well but could not make the most of early opportunities and were made to pay when Luke Thomas set up Schmidt to open the scoring.